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Administrative data

Key value for chemical safety assessment

Additional information

Cloquintocet-mexyl technical has been evaluated for possible mutagenic activity in a range of assays including both in vitro and in vivo studies and covering a range of core endpoints (gene mutation, clastogenicity, DNA repair). The key studies are considered to be those for gene mutation in bacteria (Sokolowski 2010) and in mammalian cells (Dollenmeier 1987), and those for clastogenicity both in vitro (Ogorek 1998) and in vivo (Strasser 1987).

In vitro evaluation

The test substance was examined in four strains of S typhimurium (TA 1535, TA 1537, TA98 and TA100) and two strains of E coli (E. coli WP2 pKM 101 and E. coli WP2 uvr A pKM 101), in both the absence and presence of auxiliary metabolic activation (S9) (Sokolowski 2010). Cloquintocet-mexyl was negative in this assay. A negative result was also reported in an earlier supporting study on the same four Salmonella strains and E coli strain WP2 uvr A (Deparade 1990). the test substance was examined for gene mutation in mammalian cells using the HPRT locus in V79 cells, and at dose levels limited by toxicity in both the absence and presence of S9 (Dollenmeier 1987). Cloquintocet-mexyl was negative in this assay. The test substance was examined for clastogenic activity in CHO cells, again at dose levels limited by toxicity and solubility in both the absence and presence of S9 (Ogorek 1998). Cloquintocet-mexyl was negative in this assay. This finding confirmed an earlier supporting cytogenetic study using human lymphocytes (Strasser, 1987a). Negative results for Cloquintocet-mexyl were also obtained in supporting studies examining for the DNA repair endpoint in both rat hepatocytes (Hertner 1987) and human fibroblasts (Meyer, 1987).

Cloquintocet-mexyl has been thoroughly examined in a range of in vitro mutagenicity assays and shown to be negative.

The in vitro studies are summarised below. Key studies are shown in bold.

Study

Concentrations/ Dose levels

Results

Reference

Salmonella/E. coli in vitro

0 to 5000 µg/plate,  +/-activation

negative

Deparade, 1990

Salmonella/E. coli in vitro

0 to 5000 µg/plate,  +/-activation

negative

Sokolowski, 2010

Gene mutation in V79 cells in vitro

0 to 250 µg/mL, - activation

0 to 500 µg/mL, + activation

negative

Dollenmeier, 1987

Cytogenetic test in human lymphocytes in vitro

0 to 75 µg/mL, - activation

0 to 190 µg/mL, + activation

negative

Strasser, 1987

Cytogenetic test on Chinese hamster ovary cells in vitro

0 to 25 µg/mL, - activation

0 to 50 µg/mL, + activation

negative

Ogorek, 1998

DNA repair in rat hepatocytes in vitro

0 to 200 µg /ml

negative

Hertner, 1987

DNA repair in human fibroblasts in vitro

0 to 60 µg/mL
no activation

negative

Meyer, 1987

 

In vivo evaluation

Cloquintocet-mexyl has been examined in the Chinese hamster bone marrow micronucleus assay, which can detect both clastogenic and aneugenic activity, in both male and female animals at doses up to 2500 mg/kg (Strasser, 1987). Cloquintocet-mexyl was negative in this assay.


Short description of key information:
The mutagenic potential of cloquintocet-mexyl has been assessed in a number of core genotoxicity assays in vivo and in vitro, covering a range of endpoints including gene mutation, DNA repair and clastogenicity. The data indicate that the test material is not genotoxic.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Cloquintocet-mexyl showed no evidence of genotoxicity in vitro or in vivo and does not warrant classification for this end point:

- under Directive 67/548/EEC, as amended for the 28th time in Directive 2001/59/EC, Annex VI, 4.2.2.

- under Regulation (EC) 1272/2008, Annex I, Part 3, 3.5.2.